Conventionally, there has been known a multi-type air conditioner as a refrigeration apparatus in which a plurality of indoor units are connected to a single outdoor unit through refrigerant piping so as to be arranged in parallel with one another, as disclosed in the Japanese Patent Application Laid Open Gazette No. 3-186157. The outdoor unit has a compressor, a four-way selector valve, two outdoor heat exchangers, an outdoor motor-operated expansion valve and a receiver. The indoor unit has an indoor motor-operated expansion valve and an indoor heat exchanger. The outdoor heat exchangers are each connected at an end thereof to the discharge and inlet sides of the compressor through the four-way selector valve so as to be switchable between the two sides of the compressor by the four-way selector valve. The outdoor heat exchangers is each connected at the other end to a liquid line. The liquid line is connected to an end of the indoor heat exchanger. The discharge side and the inlet side of the compressor are connected to a high-pressure gas line and a low-pressure gas line, respectively. The high-pressure and low-pressure gas lines are connected to the other end of the indoor hear exchanger so as to be switchable therebetween.
At a cooling operation, refrigerant discharged from the compressor is circulated, in such a manner as to be condensed at the outdoor heat exchanger, reduced in pressure at the indoor motor-operated expansion valve, evaporated at the indoor heat exchanger and then returned to the compressor. At a heating operation, refrigerant discharged form the compressor is circulated, in such a manner as to be condensed at the indoor heat exchanger, reduced in pressure at the outdoor motor-operated expansion valve, evaporated at the outdoor heat exchanger and then returned to the compressor.
When the indoor units perform a cooling operation and a heating operation at the same time, for example, when two indoor units perform cooling operations and the other two indoor units perform heating operations, one of the outdoor heat exchangers serves as a condenser according to an indoor load and the other outdoor heat exchanger serves as an evaporator.